Process for uniting materials.



G. c. KNAUFF.

PROCESS FOR UNITING MATERIALS. APPLICATION FILED MAR. 11, 1912.

' 1,165,68Uh Patented Dec. 28, 1915.

- 2 SSSSSSSSS EET I.

., all! tight driving fit for holding them. Neither GEORGE C. KNA'UFF, OF CHICAGO, ILLINOIS.

rEocEss Eon UNITING MATERIALS.

Specification of Letters latent.

Patented Dec. 28,

Application filed March 11, 1912. Serial No. 683,058.

To all whom it may concern Be it known that I, GEORGE C. KNAUFI, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Processes for Uniting Materials, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, forming a part of this specification.

My invention relates to processes for uniting dissimilar materials to one another, its object being to obtain a secure and rigid fastening without the use of cement or auxiliary retaining members.

It consists essentially in softening one of the materials which are to be joined, forcing the other material into it, and utilizing the contractive for ce of the softened material when hardening for gripping "the other material.

My invention is particularly applicable to the construction of articles made in part of hard rubber compositions, as for instance in securing the anchoring pins to the rubber plugs used with automobile lighting circuits. In securing such pins to the rubber bodies, it has heretofore been customary either to cement them in place, or to depend on a of these methods-have proven satisfactory with changes in the temperature and humidity of the air to which articles of this class are exposed. Instead of depending on such a driving fit or on the use of cement, I

. have found that I can obtain a more secure union of dissimilar materials by softening one of the same and utilizing the pressure due to the contraction of the softened material when hardening.

My invention'is particularly adapted for making a firm union between a membermade" of insulating material and another member made of metal, and is shown 1n this application in the accompanying drawing, forming a part of this. application.

. In the drawings, Figure 1 shows an elevation of an attachment plug before the metal member is inserted, a part of the plug bemg cut away to show a section of the interior.-

an alternative form of metal member. Figs. 5 and 6 are sections along lines 5-5 and 6-6 in Flg. 4. Fig. 7 shows a partial section of aplug with perforations passing part way through the same. Fig. 8 shows a metal member united with a rubber plate by my process. Fig. 9 shows the method of inserting the metal member shown in Fig. 2 in the plug shown in Fig. 1. Fig. 10 shows the method of cutting off the surplus length of the metal meniber required for inserting the same by the method shown in Fig. 9.

In the drawings, A is an attachment plug of hard rubber, having a body B with a transverse perforation C. D is a metal member having a section at both ends substantially equal in size to the bore of the perforation C. E is a raised thread formed on the central portion of the member D. To insert this member D in the perforation C, I soak the rubber body D for some time in water heated close to its boiling point (or to about 205 degrees Fahrenheit), thereby eX- panding the rubber and softening its surface portions, including the wall of the perforation, toa state in which they are plastic or pliable, but not fiuid. I then grasp one end F of the member D between the jaws of the chuck G of a drill press H as shown in Fig.

' 9 and rotate thechuck while the body B is kept from turning by resting in a non-rotatable grooved support I. On raising this support while the member D is being rotated, the thread E compresses the softened portions of the rubber body B adjoining the perforation, thereby allowing the member D to thread its way through the body B. Then, when the assembled parts B and D are allowed to cool, the rubber contracts in hardening, thereby gripping the surface of the thread E so tightly that I have found it impossible to separate the united members B and D as in Fig. 3 without damaging the former.

In carrying out my process, I preferably give the member which is to be inserted a cylindrical form and roll raised threads upon the same. The length of the threaded portion of the insertible member is preferably made somewhat less than the length of the perforation. Then when-the said member is inserted until the perforated member completely houses the threaded portion of the other member (asin Fig. 3) the portions .of the perforated member at each end of the perforation will contact with unthreaded portions of the inserted member. material hardens, it will form contracted portions around the inserted material at each end of the perforation, which portions will act as stops to prevent the unscrewing of the inserted member. However, I have found that instead of rolling the thread upon the member which is to be inserted in the other material, the central portion of the insertible member may be stamped out as in Fig. 2, and provided at opposite edges with staggered teeth J, which will press back the rubber and thread their way intothe softened walls of the perforation (1, thus serving the same purpose as the form shown in Fig. 2. I have also found that my process serves equally well with perforations extending only part way throu h the softenable body as shown 1n Fig. in which K is a perforation entering the body from one side and L is a metal member inserted into a corresponding open- .i w on the other side of the plug M.

, have also found that my process will serve equally well for uniting metal members with sheets of insulating material, as shown in Fig. 8, in which N is a plate of hard rubber, and O is a metal switch pivot inserted in the same by my process. In thus securing metal members to sheets or plates, it is not necessary to soak the whole plate in hot water, as the softening influencemay be obtained in the form of a jet of hot water. or steam sprayed upon the portions of the plate or sheet adjacent to the perforation in which the metal member is to be inserted.

For some uses of dissimilar combinations of materials, the non-softenable material must not project sufficiently beyond the surface of the softenable material to offer a proper hold for the jaws of the chuck used for rotating it, as for example in the attachment plug shown in my copending application, filed-November 20th, 1911, Serial #661375. Moreover, even if the inserted member could be grasped by the short end which projects from the finished combination, it would be difficult to stop-this in the process of insertion at just the rlght point to obtain the proper amount of projection. In such a case, I lengthen the member which is to be inserted, at one or both ends. Then, after insertion, I rest the rubber body in the socket portion of a die P as shown in Fig. 10, and cut off the projecting surplus length of the inserted member B with a die R.

While I have illustrated and described my process as applied in uniting metal to hard rubber and as using steam or hot water as the softening influence, I do not wish to be limited to the materials or the soften- Consequently, when the perforateding influences mentioned, as it will be evident that my process will be applicable to the uniting of other materials of a dissimilar nature and that other softening influences than water or steam may be used in the process; alsofthat my process is particularly applicable to amorphous materials which are normally unyielding and incompressible. v

lVhat I claim as new and desire to cover by Letters Patent is:

1. The process of uniting a non-moistureabsorptive and-normally hard body with a metal bar having end portions of uniform diameter and having a raised thread upon its surface intermediate of the said'end portions, which consists in forming in the said body a perforation smaller in bore than the outside diameter of said raised thread:

softeningcthe perforation surface parts of the body to a plastic but non-fluid state by heating the same to about 200 degrees Fahrenheit: screwing the said bar forcibly into the perforation while the said parts are in their softened state, whereby the said raised thread compresses and reshapes the said A parts of the body while being inserted: and hardening the said parts by cooling them, thereby anchoring the said bar by thepressure thereon of the said adjacent material.

2. The process of uniting a non-moistureabsorptive and normally hard body with a metal bar having end portions of uniform. diameter and having a raised thread upon- .its surface intermediate of its said end portions, which consists in forming in the said body a perforation corresponding substantially in its bore to the diameter of the said end portions, the length of the said perforation being greater than the said threaded .portion of. the bar: softening the perforation surface parts of the body by heating the same to about 200 degrees Fahrenheit: forcing the said bar into the perforation, while the adjacent surface parts of the said body are in their said softened state, until the said body completely houses the threaded portion of the bar, whereby the said raised thread compresses and reshapes the said parts of the body while the threaded portion of the bar is being inserted, and whereby the compressed portions adjacent to one end of the perforation will expand after the threaded portion of the bar has passed the said end of the perforation: and cooling the said partsto harden the same and to anchor the said bar partly by the pressure thereon of the hardened ad acent material and partly by the annular wall formed around the bar between the said end of the perforation and the adjacent end of the threaded portion of the bar.

3. The method of uniting a non-moistureabsorptive and normally hard material with a metal bar equipped with surfacev elevations, which consists in providing in the said material an opening corresponding in dimensions with the body portion of the part of, the bar to be received therein: heating the said material to about 200 degrees Fahrenheit to render the Walls of the said opening plastic but non-fluid: inserting the said portion of the bar in the said opening While the said Walls are plastic, thereby causing the said surface elevations to become embedded in the said. Walls: and then cooling the said material to cause the same to harden with the said body portion of the bar embedded therein.

d. The hereindescribed method of uniting hard rubber and a metal memberequipped With projections, which consists in providing an opening in the hard rubber corresponding substantially in lateral dimensions With the body portion of the part of the said member to be received therein: exposing said hard rubber to a temperature of about 200 degrees Fahrenheit for a sufficient time to render the Walls of the said opening pliable: inserting the said part of the member in the perforation With a gradually advancing rotary motion, thereby causing the said projection threadedly to embed themselves in the Walls of the perforations: then allowing said rubber to cool and harden With the said body portion of the metal member embedded therein. 1

5. The method of rigidly embedding in a normally brittle amorphous body a metal member having a portion equipped With at least one projection, Which consists in providing an opening in said body of less transverse dimensions than the greatest transverse dimensions of the said portlon of the metal member, subjecting the said body to the action of a heating influence at about 200 degrees Fahrenheit to render the peripheral Wall of the opening plastic, but nonfluid, inserting said projection-bearing part of said'member in said opening While the 1 nesses:

O. KNAUFF. Witnesses ALBERT SCHAIBLE, M. A. SMITH, Jr. 

